Fluid power actuated hand clamp



May 8, 1951 c. K. ARTER, JR

FLUID POWER ACTUATED HAND CLAMP Filed Jan. 9, 1946 INVENTOR. CHHPLES A? flew/FA 147- roens Y5 Patented May 8, 1951 UNITED STATES PATENT OFFICE FLUID POWER ACTUATED HAND CLAMP Charles K. Arter, J r., Shaker Heights, Ohio Application January 9, 1946, Serial No. 639,966

This invention relates to improvements in power clamps, particularly G-clamps operated by pressure fluid such as compressed air.

One of the objects of the invention is the provision of a clamp which may be operated much more rapidly than the conventional screw clamp, and yet grip the work firmly.

Another object is the provision of control means which will function automatically to hold the clamp closed except when the control is manually operated. Hence it is unnecessary for the operator to use one hand to keep the clamp in closed condition, and both hands are their free when needed to perform operations upon the work held by the clamp.

Another object is the provision of means disposed entirely within the power cylinder and its end walls for causing live and exhaust fluid to flow into and out of the spaces within the cylinder on opposite sides of the piston therein.

A further object is the provision of a C-clamp, the capacity of which may be varied by substituting C-members of different lengths, and in which the angular relation of the C-member may be changed to suit conditions.

Still another object is the provision in a power cylinder having'end walls threadably connected thereto of a manually operable control bar extending the full length of the cylinder connected with a control valve at one end wall and with a rotatably adjustable plate engaging the other end wall, whereby the control bar may be assembled and maintained in proper position parallel to the axis of the cylinder.

Another object is the provision or removable and replaceable anvil elements which may be interchangeably employed, including such an element for mounting the clamp in an upright position upon a bench or the like.

Other objects and features of novelty will appear as I proceed with the description of that embodiment of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawing, in which Fig. 1 is an elevational view, partly in central longitudinal section, of a c-clamp embodying the invention,

Figs. 2 and 3 are cross-sectional views taken substantially on the lines 2-2 and 33 of Fig. 1,

2 Claims. (01. 144305) 2 V Fig. 4 is a cross-sectional view taken substantially on the ilne 4-4 of Fig. 1, and

Fig. 5 is a fragmental elevational view showing the clamp mounted in an upright position on a bench or the like.

In the drawing a power cylinder shown at I0 is provided with end walls It and I2 threadably connected thereto. Piston I3-is mounted to slide within the cylinder and is sealed against the flow of pressure fluid in either direction by means of packing l4.

On the inner side of end wall I I there is a metal washer 15 held at its periphery by the threaded joint between the cylinder [0 and end wall ll,

and serving to retain packing l6 of any suitable character, which seals the sliding joint around a plunger [1 having a reduced diameter portion l8 that extends through the piston and through a large washer 19, a nut 26 being threaded onto the extremity of the reduced portion E8 to form a rigid connection between the piston and the plunger.

Plunger 51 extends through a central opening in end wall II and through a tubular extension 2! formed integral with that all. A flat plate,22 having a circular opening therethrough, of a size to receive extension 2| is mounted on that extension. This plate is provided with a projecting portion 23 which extends slightly beyond the periphery of end wall II, where it has hinged thereto a control bar 24 that extends substantially the fulll ength of the cylinder.

The C-member 25 of the clamp is formed at the extremity of its inner arm with a cylindrical enlargement 26 which is bored to receive cylindrical extension 2|. The hub of this enlargement bears against plate 22. A nut 27! is threaded onto the end of extension 2 I, and when turned down tightly serves to hold plate 22 and C-member 25 firmly in any selected angular position relative to the assembled cylinder I 0 and end walls II and I2.

The extremity of the outer arm of C-member 25 may be finished in the conventional manner of clamps of this sort, but I prefer to form this extremity as a cylindrical enlargement 28 more or less similar to the enlargement 26. This enlargement 28 has a hole 29 therethrough which takes the shank of a bolt 30 with a hard steel head or anvil 3| which is held in place by a nut 32 threaded onto the outer end of the bolt. Anvil 3! is of course centered with respect to plunger H. In case the clamp is to be used upon work of irregular configuration, a bolt with a special head conforming to the contour of the work may be substituted for the one shown.

This removable bolt feature of my invention has another important advantage illustrated in Fig. 5 of the drawing, where a bolt having a longer shank is employed for fastening the clamp in an upright position to a bench top 33 or the like.

Since hard metal is employed in the parts I! and 3| the C-member 25 may be formed of lighter and less wear resistant material if desired.

At an intermediate point in its length G-member 25 may have an integral boss with opposed flat surfaces 3 through which a hole 3 is bored. When it is desired to mount the clamp in a horizontal position on a bench this boss may be gripped in the jaws of a vise, or it may be fastened to a bench by a bolt passed through the hole 9 and through a hole in the bench.

The capacity of the work which may be handied by the clamp depends upon the distance between the extremity of cylindrical extension 25 and the anvil 31 of bolt 39 in the outer arm of the c-member. This capacity may be increased by substituting for the C-member shown one that is longer. Similarly, work of a smaller nature can be handled by the same tool with a shorter C-member inserted in place of the member illustrated. The C-member 25 and the plate 22 are adjustable angularly independently of each other.

Although the piston 13 may be caused to move in on direction by means of a spring, not shown, the disclosure herein contemplates moving the piston in both directions by means of pressure fluid. To this end a cylindrical valve chamber 34 is formed in end wall E2 to receive a spool valve 35 which has an axially disposed stem 33 that has a loose connection with the rear end of control bar 24, permitting movement of the bar without binding from the position illustrated to a position closely approaching the end wall 12. A coil spring 31 surrounding stem 36 tends to hold stem 33 and valve 35, as well as control member 24, in their outermost positions.

The operation of valve stem 36 by a bar 24 which extends along the cylinder It substantially throughout its length facilitates the use of the tool, since the operator may grasp the cylinder as a handle at any point along its length, his fingers extending over the control bar 24. The size of the operators hand will determine the point at which it will be most comfortable for him to grasp the tool. The two threaded connections between the cylinder l3 and the end walls I l and I2, when the latter are tightened down in the assembly of the device will cause some variation in the angular relation of these parts in dillerent tools. On this account the bar 24 instead of being hinged to end wall H is hinged to the separate plate 22, the angular position of which is adjustable to bring the hinge into proper relation with the stem 38, after which the plate is locked by nut 21 as previously explained.

Valve chamber 34 has a central connection at 38 with a fitting 39 for a flexible tube 49 through which compressed air or other pressure fluid may be delivered to the power cylinder. 4! and 42 are exhaust passages. A passage 43 connects the valve chamber 34 with a cylinder space 44 to the ill rear of piston 13. A passage 45 in end wall (2 establishes communication between chamber 34 and a tube 43 which is mounted in the end wall and is disposed parallel to the axis of cylinder I3 and extends through washer l9 and piston 3 with sufiicient clearance to minimize friction. A cavity 4? in piston [3 receives packing 48 which surrounds tube 46 and is held in place by washer 19. The sliding joint is therefore sealed. The forward end of tube 43 extends well into the cylinder space 49 in front of the piston.

Operatio1t.-With the parts in the position illustrated in Fig. 1, any piece of work W will be tightly gripped since pressure fluid Will flow from the supply line through tube 43 into valve chamber 34 and thence through passage 43 into cylinder space 44, causing the piston [3 to move to the left until plunger ll is stopped by its engagement with the work. This gripping of the work will continue as long as may be required and without any control being exercised by the operator. Now when the operator desires to release the work W he pulls the control bar 24 inwardly toward the cylinder It by means of the fingers of the hand which holds the cylinder, thereby shifting the valve piece 35 downward, as viewed in the drawing until the upper end of the spool moves downward beyond passage 43 and the lower end moves downward beyond the passage 45. Passage 43 will then communicate with exhaust connection 4i, relieving the pressure in cylinder space 44, and live fluid will flow from the supply through the reduced diameter part of the valve into passage 45 and through tube 46 to the cylinder space 49. This will cause the piston I3 to move rearwardly, pulling the plunger away from the work. As soon as the operator releases his hold upon the control bar 24, spring 31 will again return the parts to the illustrated position or to whatever position the thickness of the work being gripped will permit.

Having thus described my invention, I claim:

1. In combination, a power cylinder having end walls one of which is threaded on the cylinder, one of said end walls having an opening therethrou-gh surrounded by a cylindrical extension, a laterally extending valve element on the other end wall, a piston within said cylinder, a plunger attached to said piston projecting through said opening and cylindrical extension, a clamp C-member rotatably mounted on said cylindrical extension, a plate rotatably mounted on said extension between said G-member and the adjacent end wall of the cylinder, control means articulated with said plate adapted to engage said valve element when said plate is in proper angular position, and means for locking said G-member and plate against angular movement on said extension.

2. In a power operated clamp, a power cylinder having end walls threadably connected therewith, a fluid valve carried by one of said end Walls, a laterally extending valve operating element on said end wall, the other end wall having a hollow central projection of circular crosssection, a plate rotatably mounted on said projection, a clamp member also mounted on said circular extension, said power cylinder having a piston and a plunger xtending through said hollow extension for cooperation with said clamp member, a control member articulated with said plate and having an operative connection with said laterally extending valve operating element,

7 and means for locking said plate in a selected angular position relative to the assembled cylinder and end Walls.

CHARLES K. ARTER, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Morgan May 6, 1884 Fielding May 2, 1899 Merralls Sept. 8, 1908 Hammar Apr. 20, 1915 Number Number France Jan. 15, 1937 

